In an apparatus provided with a plurality of electronically controllable devices, communication is performed between processors that individually control the devices. For example, a vehicle such as an automobile is provided with an air conditioner, door mirrors, power windows, wipers, and other electronically controllable devices. A plurality of Electronic Control Units (ECU) that electronically control these devices are mounted in the vehicle. These ECUs are connected to each other by a bus and communicate according to a predetermined communication protocol.
During communication between the ECUs, noise might be emitted by wiring in the bus that connects the ECUs. The emitted noise might affect other devices depending on the frequency band.